vsock enables communication between virtual machines and the host they are running on. Nested VMs can be setup to use vsock channels, as the multi transport support has been available in the mainline since the v5.5 Linux kernel has been released.
Implicitly, if no host->guest vsock transport is loaded, all the vsock packets are forwarded to the host. This behavior can be used to setup communication channels between sibling VMs that are running on the same host. One example can be the vsock channels that can be established within AWS Nitro Enclaves (see Documentation/virt/ne_overview.rst). To be able to explicitly mark a connection as being used for a certain use case, add a flag field in the vsock address data structure. The "svm_reserved1" field has been repurposed to be the flag field. The value of the flag will then be taken into consideration when the vsock transport is assigned. This way can distinguish between nested VMs / local communication and sibling VMs use cases. And can also setup one or more types of communication at the same time. Thank you. Andra --- Patch Series Changelog The patch series is built on top of v5.10-rc6. GitHub repo branch for the latest version of the patch series: * https://github.com/andraprs/linux/tree/vsock-flag-sibling-comm-v1 --- Andra Paraschiv (3): vm_sockets: Include flag field in the vsock address data structure virtio_transport_common: Set sibling VMs flag on the receive path af_vsock: Assign the vsock transport considering the vsock address flag include/uapi/linux/vm_sockets.h | 18 +++++++++++++++++- net/vmw_vsock/af_vsock.c | 15 +++++++++++---- net/vmw_vsock/virtio_transport_common.c | 8 ++++++++ 3 files changed, 36 insertions(+), 5 deletions(-) -- 2.20.1 (Apple Git-117) Amazon Development Center (Romania) S.R.L. registered office: 27A Sf. Lazar Street, UBC5, floor 2, Iasi, Iasi County, 700045, Romania. Registered in Romania. Registration number J22/2621/2005.
